//  Copyright 2017 Google Inc. All Rights Reserved.
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.

package main

import (
	"os"
	"syscall"
	"unsafe"
)

const blkGetSize64 = 0x80081272

func diskLength(file *os.File) (int64, error) {
	var size int64
	if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, file.Fd(), blkGetSize64, uintptr(unsafe.Pointer(&size))); err != 0 {
		return 0, err
	}
	return size, nil
}
